| Nomenclature and abbreviations | |
|---|---|
| Latin letters | |
| D | Pipe inner diameter [m] |
| d | Orifice (bore) diameter [m] |
| h | Orifice plate thickness [m] |
| e | Orifice bore thickness after chamfering [m] |
| U | Inlet mean velocity [m·s−1] |
| P | Static pressure [Pa] |
| ΔP | Differential pressure across the orifice plate [Pa] |
| Δπ | Permanent pressure loss [Pa] |
| Cd | Discharge coefficient |
| Greek letters | |
| α | Upstream chamfer (bevel) angle [°] |
| β | Diameter ratio, β = d/D |
| μ | Dynamic viscosity [Pa·s] |
| ν | Kinematic viscosity [m2·s−1] |
| ρ | Density [kg·m−3] |
| ξ | Pressure loss coefficient |
| Dimensionless groups | |
| Re | Reynolds number, Re = ρUD/μ |
| t | Relative plate thickness, t = h/d |
Fig. 1.
Schematic diagram of a throttling orifice plate.
Fig. 2.
Computational setup for the chamfered orifice plate simulations: (a) computational domain with straight pipe extensions of 10D upstream and 10D downstream; (b) local schematic of the orifice plate region, showing the geometric parameters and pressure tap locations used to define ΔP (upstream tap tu and downstream tap td).
Fig. 3.
Geometric definition of a chamfered orifice plate: pipe diameter D, orifice diameter d, plate thickness h, orifice bore thickness e, and chamfer angle α.
Fig. 4.
Poly-hexcore mesh and local refinement strategy for the orifice plate simulations.
Fig. 5.
Grid independence assessment based on the differential pressure ΔP across the orifice plate.
Fig. 6.
Comparison of the discharge coefficient Cd between the ISO 5167 reference values and CFD predictions.
Table 1.
Structural parameters of throttled orifice plates with different thicknesses.
| Throttle orifice d [mm] | Beta ratio β | Thickness h [mm] | Relative thickness t |
|---|---|---|---|
| 30 | 0.6 | 3 | 0.10 |
| 30 | 0.6 | 5 | 0.17 |
| 30 | 0.6 | 7 | 0.23 |
| 30 | 0.6 | 10 | 0.33 |
| 30 | 0.6 | 15 | 0.50 |
| 30 | 0.6 | 30 | 1.00 |
| 30 | 0.6 | 36 | 1.20 |
Fig. 7.
Axial velocities of throttled orifice plates of different thicknesses.
Fig. 8.
Velocity clouds for different thicknesses of throttled orifice plates.
Fig. 9.
Effect of orifice plate thickness and Reynolds number on the orifice plate pressure loss coefficient.
Fig. 10.
Trace distribution of thin and thick orifice plates.
Table 2.
Orifice plate chamfering parameters.
| Thicknesses h [mm] | Orifice bore thickness e [mm] | Chamfer angle α [°] |
|---|---|---|
| 3 | - | 90 |
| 3 | 1 | 15 |
| 3 | 1 | 30 |
| 3 | 1 | 45 |
| 3 | 1 | 60 |
Fig. 11.
Velocity change curves for standard and chamfered orifice plates.
Fig. 12.
Pressure loss coefficient versus chamfer angle at different Reynolds numbers.
Fig. 13.
Flow field traces of throttled orifice plates with different chamfer angles.
Table 3.
Chamfered orifice plate structure parameters.
| Diameter ratio β | Thicknesses h [mm] | Orifice bore thickness e [mm] | Chamfer angle α [°] |
|---|---|---|---|
| 0.6 | 3 | 1 | 15 |
| 0.6 | 3 | 1 | 30 |
| 0.6 | 3 | 1 | 45 |
| 0.6 | 3 | 1 | 60 |
| 0.6 | 3 | 2 | 15 |
| 0.6 | 3 | 2 | 30 |
| 0.6 | 3 | 2 | 45 |
| 0.6 | 3 | 2 | 60 |
| 0.6 | 3 | 3 | 15 |
| 0.6 | 3 | 3 | 30 |
| 0.6 | 3 | 3 | 45 |
| 0.6 | 3 | 3 | 60 |
Fig. 14.
Pressure loss coefficients for different chamfered structure orifice plates.